Optoelectronic semiconductor device

ABSTRACT

An optoelectronic semiconductor device has a semiconductor body including a semiconductor layer sequence with an active region that generates radiation, a semiconductor layer and a further semiconductor layer, wherein the active region is arranged between the semiconductor layer and the further semiconductor layer, a current spreading layer is arranged on a radiation exit face of the semiconductor body, the current spreading layer connects electrically conductively with a contact structure for external electrical contacting of the semiconductor layer, in a plan view of the semiconductor device the current spreading layer adjoins the semiconductor layer in a connection region, and the current spreading layer includes a patterning with a plurality of recesses through which radiation exits the semiconductor device during operation.

TECHNICAL FIELD

This disclosure relates to an optoelectronic semiconductor device.

BACKGROUND

In radiation-generating semiconductor devices such as, for example,light-emitting diodes, contact layers are often applied over a largearea on a side on which the radiation exits during operation to bringabout the largest possible area of charge carrier injection. However,even when radiation-transmissive materials, for example, transparentconductive oxides (TCOs) are used, a significant proportion of the lightis lost through absorption on passage through such a contact layer.

It could therefore be helpful to provide an optoelectronic semiconductordevice distinguished by reduced absorption losses at the same time asgood charge carrier injection.

SUMMARY

We provide an optoelectronic semiconductor device having a semiconductorbody including a semiconductor layer sequence with an active region thatgenerates radiation, a semiconductor layer and a further semiconductorlayer, wherein the active region is arranged between the semiconductorlayer and the further semiconductor layer, a current spreading layer isarranged on a radiation exit face of the semiconductor body, the currentspreading layer connects electrically conductively with a contactstructure for external electrical contacting of the semiconductor layer,in a plan view of the semiconductor device the current spreading layeradjoins the semiconductor layer in a connection region, and the currentspreading layer includes a patterning with a plurality of recessesthrough which radiation exits the semiconductor device during operation.

We also provide an optoelectronic semiconductor device having asemiconductor body including a semiconductor layer sequence with anactive region that generates radiation, a semiconductor layer and afurther semiconductor layer, wherein the active region is arrangedbetween the semiconductor layer and the further semiconductor layer, acurrent spreading layer is arranged on a radiation exit face of thesemiconductor body, the current spreading layer connects electricallyconductively to a contact structure for external electrical contactingof the semiconductor layer, in a plan view of the semiconductor device,the current spreading layer adjoins the semiconductor layer in aconnection region, the current spreading layer includes a patterningwith a plurality of recesses through which radiation exits thesemiconductor device during operation, and the patterning includestrench-shaped recesses with ribs of the current spreading layerextending between the trench-shaped recesses and a crosswise extent ofthe trench-shaped recesses decreases at least in places as the distancefrom the contact structure increases.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B show an example of an optoelectronic semiconductordevice in schematic plan view (FIG. 1A) and associated sectional viewalong line A-A′ (FIG. 1B).

FIGS. 1C and 1D show further examples of an optoelectronic semiconductordevice in schematic sectional view.

FIGS. 2A to 2J each show examples of a patterning on the basis of aportion 91 of FIG. 1A illustrated on an enlarged scale.

FIG. 3 shows an example of a patterning on the basis of a furtherportion 92 of FIG. 1A.

FIG. 4 shows a luminance distribution of a semiconductor device.

DETAILED DESCRIPTION

Our optoelectronic semiconductor device generates electromagneticradiation in particular when the semiconductor device is in operation.

The semiconductor device may have a semiconductor body with asemiconductor layer sequence. The semiconductor layer sequence comprisesan active region that generates radiation. The active region is, forexample, provided in the ultraviolet, visible and/or infrared region ofthe spectrum. For example, the active region is arranged between asemiconductor layer and a further semiconductor layer of thesemiconductor layer sequence. The semiconductor layer and the furthersemiconductor layer are conveniently different from one another at leastin places with regard to conduction type such that the active region issituated in a pn junction.

The semiconductor body further comprises a radiation exit face extendingparallel to a main plane of extension of the semiconductor layers of thesemiconductor layer sequence. The radiation exit face terminates thesemiconductor body in a vertical direction, i.e., perpendicular to amain plane of extension of the semiconductor layers of the semiconductorlayer sequence. For example, the semiconductor layer forms the radiationexit face.

The optoelectronic semiconductor device may comprise a current spreadinglayer. The current spreading layer is arranged in particular outside thesemiconductor body, for example, on the radiation exit face. The currentspreading layer is, for example, configured to be radiation-transmissiveto the radiation generated in the semiconductor device. For example, thecurrent spreading layer contains a TCO material.

The optoelectronic semiconductor device may comprise a contact structurefor external electrical contacting of the semiconductor layer. Thecontact structure in particular connects electrically conductively tothe current spreading layer. For example, the semiconductor devicecomprises a further contact structure for external electrical contactingof the further semiconductor layer. Through application of an electricalvoltage between the contact structure and the further contact structure,charge carriers may be injected from different sides into the activeregion and there recombine with emission of radiation.

In a plan view of the semiconductor device, the current spreading layermay adjoin the semiconductor layer in a connection region. Theconnection region defines that region on the radiation exit face inwhich charge carrier injection takes place from the current spreadinglayer into the semiconductor layer. In the plan view, the currentspreading layer extends in particular within an enveloping outer borderof the connection region. In case of doubt, an enveloping outer borderis considered to be the imaginary course of an elastic band extendingalong the outer faces of the current spreading layer.

The current spreading layer may comprise a patterning with a pluralityof recesses, in particular within an enveloping outer border of theconnection region. Within the outer border of the connection region, thecurrent spreading layer is thus not arranged with a homogeneousthickness over the entire area of the radiation exit face. Inparticular, when the semiconductor device is in operation, radiationexits from the semiconductor device through the recesses. Regions inwhich the semiconductor body is covered by the contact structure and inwhich there is no underlying current spreading layer are, on the otherhand, not considered to be recesses for our purposes. Likewise, regionsin which the radiation exit face itself has an indentation, for example,to electrically contact the further semiconductor layer by the furthercontact structure, do not constitute recesses of the current spreadinglayer in the connection region.

The optoelectronic semiconductor device may comprise a semiconductorbody comprising a semiconductor layer sequence with an active regionthat generates radiation, a semiconductor layer and a furthersemiconductor layer. The active region is arranged between thesemiconductor layer and the further semiconductor layer. A currentspreading layer is arranged on a radiation exit face of thesemiconductor body. The current spreading layer connects electricallyconductively to a contact structure for external electrical contactingof the semiconductor layer. In plan view onto the semiconductor device,the current spreading layer adjoins the semiconductor layer in aconnection region. The current spreading layer comprises a patterningwith a plurality of recesses through which radiation exits thesemiconductor device during operation.

The recesses are formed in particular within an enveloping outer borderof the connection region.

The recesses comprise a lengthwise extent, for example, in alongitudinal direction in which they have a maximum extent. Furthermore,the recesses have a crosswise extent perpendicular to the longitudinaldirection. In circular recesses, the lengthwise extent is equal to thecrosswise extent.

The crosswise extent may be conformed to a transverse conductivity ofthe semiconductor layer such that, in a plan view of the semiconductordevice, charge carriers are injected via the semiconductor layer intothe active region at every location in the recesses when thesemiconductor device is in operation. The crosswise extent of therecesses is thus merely of such magnitude that the active region is alsocompletely energized within the recesses in plan view onto thesemiconductor device.

In particular, it is ensured that regions do not form as a result of therecesses in the active region which are not energized and causeradiation absorption. Such absorption effects might more than compensatefor the reduced absorption in the current spreading layer due to therecesses. In the connection region the maximum distance to the currentspreading layer is thus so small at every location in the cutouts thatcharge carriers can bridge this distance due to the transverseconductivity of the semiconductor layer.

The recesses may at least partly be elongate when viewed in a plan viewof the semiconductor device. For example, the recesses have a lengthwiseextent in the longitudinal direction which is at least 20% greater thanthe crosswise extent in a transverse direction extending perpendicularto the longitudinal direction. Even in a lengthwise extent of therecesses which is very much greater than the crosswise extent of therecesses, efficient charge carrier injection into the active region maytake place in the recesses. For example, the extent in the longitudinaldirection is at least twice as great or at least five times as great asthe crosswise extent. The recesses may, for example, have an ellipticalor trench-like basic shape. For example, a plurality of recessesconfigured in the shape of trenches and extending parallel to oneanother form a comb-shaped structure. The recesses, in particulartrench-like recesses, may also extend as far as the outer border of theconnection region. Alternatively, the recesses may extend completelyinside the connection region when viewed in plan view onto thesemiconductor device. In recesses of elongate configuration, thelongitudinal direction preferably extends in a local preferentialdirection of the current in the current spreading layer. For example,the longitudinal directions of the recesses extend along the shortestconnection between the contact structure and the further contactstructure at the respective location. In this way, the current pathinside the current spreading layer and the series resistance resultingfrom the current spreading layer are minimized.

The patterning may comprise trench-like recesses with ribs of thecurrent spreading layer extending between the trench-like recesses. Inparticular, a crosswise extent of the trench-like recesses decreases atleast in places as the distance from the contact structure increases.For example, the crosswise extent of the trench-like recesses decreasescontinuously. For example, a crosswise extent of the trench-likerecesses and/or a crosswise extent of the ribs varies in the connectionregion by at least 20%, preferably by at least 50%.

An area of the recesses and/or a center-to-center distance of therecesses may vary when viewed in a plan view of the semiconductordevice. In other words, coverage of the semiconductor layer withmaterial of the current spreading layer varies in the lateral direction.In the event of a variation in the area of the recesses, preferably allthe recesses are adapted, in terms of their crosswise extent, to thetransverse conductivity of the semiconductor layer such that, in theplan view of the semiconductor device, charge carrier injection into theactive region takes place at every location within the recesses.

In case of doubt, the spacing of the respective centroids of therecesses is considered to be the center-to-center distance of therecesses.

As the distance from the closest contact structure increases, inparticular the area of the recesses decreases and/or thecenter-to-center distance of the recesses increases. Regions arrangedclose to the contact structure are thus covered with a smaller volume ofthe material of the current spreading layer than regions arrangedfurther away from the contact structure.

The connection region may comprise a first square area and a secondsquare area. The first square area and the second square area eachconstitute sub-regions of the current spreading layer, wherein the firstsquare area and the second square area are of equal size and each havean edge length greater than or equal to twice the crosswise extent ofthe recesses in the first square area. When viewed in a plan view of thesemiconductor device, the recesses in the first square area fill atleast 20% of the first square area and the recesses in the second squarearea fill at most 10% of the second square area. The first square areaand the second square area are each arranged completely within the outerborder of the connection region. The first square area and the secondsquare area may in particular serve as a measure of the variation incoverage of the connection region with material of the current spreadinglayer.

In this case, the first area is in particular arranged closer to aclosest point of the contact structure than the second area. Inparticular, the first area may be situated in a current path between theclosest point of the contact structure and the second area.

The recesses may not extend completely through the current spreadinglayer in a vertical direction. The current spreading layer thus adjoinsthe semiconductor layer even in the region of the recesses. Large-areacharge carrier injection into the semiconductor layer is thussimplified.

The recesses may take the form of cutouts extending right through thecurrent spreading layer. Such recesses are particularly simple toproduce. Furthermore, the radiation generated in the active regionduring operation does not have to pass through any material of thecurrent spreading layer in the region of the cutouts. The fraction ofthe radiation absorbed in the current spreading layer is thus reduced.

In a plan view of the semiconductor device, the patterning containsoptical information. The optical information may, for example, take theform of one or more characters and/or symbols. The optical informationis preferably configured such that it is distinguishable under a lightmicroscope.

The patterning may comprise at least one first recess and one secondrecess, wherein the first recess and the second recess differ from oneanother in their base area when viewed in the plan view of thesemiconductor device. For example, the first recess and the secondrecess have a different shape and/or a different area.

In particular, the patterning comprises a plurality of first recessesand a plurality of second recesses, wherein information is encoded bythe first recesses and the second recesses. For example, the informationmay be digitally encoded, wherein the first recesses represent a digitalzero and the second recesses a digital one or vice versa. Furthermore,information may be encoded in the form of a barcode by trench-likerecesses.

The information may, for example, relate to production of thesemiconductor device and, for example, contain details about themanufacturer or parameters during implementation of the method. Thetraceability of the semiconductor devices is thereby improved.

The patterning may be configured such that, in a region in which currentflow locally has a preferential direction in the current spreadinglayer, the patterning favors lateral current flow in the preferentialdirection. For example, recesses of elongate construction are orientedwith their longitudinal direction in the preferential direction.

The patterning may be configured such that, in a region in which acurrent flow is locally without a preferential direction, the patterninghas no or at least no significant effect on the direction of the lateralcurrent flow. For example, the patterning may be formed by a pluralityof recesses arranged in a grid or honeycomb. Such patterning may, forexample, be convenient in a region of the connection region in which theadjacent contact structure does not extend straight and, for example,has a kink or a bend.

In particular, the semiconductor device may have at least one locationwith a patterning having an effect on the direction of the lateralcurrent flow and one location with a patterning having no effect on thedirection of the lateral current flow.

In a region of the semiconductor device in which a current density isbelow 20% of the average current density, the radiation exit face may befree of the current spreading layer to increase the radiationoutcoupling from the semiconductor device. A region of the semiconductordevice in which, for example, due to the geometry of the contactstructure and/or of the further contact structure, only comparativelyslight charge carrier injection into the underlying part of the activeregion could be achieved even in the presence of a current spreadinglayer is thus deliberately kept free of the current spreading layer inthis way to increase radiation outcoupling from the semiconductor devicein this region.

Further configurations and convenient aspects are revealed by thefollowing description of examples in conjunction with the figures.

Identical, similar or identically acting elements are provided with thesame reference numerals in the figures.

The figures and the size ratios of the elements illustrated in thefigures relative to one another are not to be regarded as being toscale. Rather, individual elements and in particular layer thicknessesmay be illustrated on an exaggeratedly large scale for greater ease ofdepiction and/or better comprehension.

FIG. 1A shows an optoelectronic semiconductor device 1 in plan view. Thesemi-conductor device takes the form of a semiconductor chip, forexample, a light-emitting diode.

The semiconductor device 1 comprises a semiconductor body with asemiconductor layer sequence 2. In a vertical direction extendingperpendicular to a main plane of extension of the semiconductor layersof the semiconductor layer sequence, the semiconductor body is delimitedby a radiation exit face 210.

The semiconductor body with the semiconductor layer sequence 2 comprisesan active region 20 that generates radiation. The active region 20 isarranged between a semiconductor layer 21 of a first conduction type anda further semiconductor layer 22 of a second conduction type differentfrom the first conduction type. The semiconductor body, in particularthe active region 20, for example, contains a III-V compoundsemiconductor material.

III-V compound semiconductor materials are particularly suitable forgenerating radiation in the ultraviolet (Al_(x) In_(y) Ga_(1-x-y) N)through the visible (Al_(x) In_(y) Ga_(1-x-y) N, in particular for blueto green radiation, or Al_(x) In_(y) Ga_(1-x-y) P, in particular foryellow to red radiation) as far as into the infrared (Al_(x) In_(y)Ga_(1-x-y) As) region of the spectrum. In each case 0≦x≦1, 0≦y≦1 andx+y≦1 applies, in particular with x≠1, y≠1, x≠0 and/or y≠0. Using III-Vcompound semiconductor materials, in particular from the stated materialsystems, it is additionally possible to achieve high internal quantumefficiencies in the generation of radiation.

For example, the semiconductor layer 21 contains p-conductively dopednitride compound semiconductor material, in particular Al_(x) In_(y)Ga_(1-x-y) N, and the further semiconductor layer containsn-conductively doped nitride compound semiconductor material.

The semiconductor layer 21 forms the radiation exit face 210. Thesemiconductor layer 21 is thus arranged between the radiation exit face210 and the active region 20.

A current spreading layer 3 is arranged on the radiation exit face 210.The current spreading layer 3 is configured to be transmissive to theradiation generated in the active region and contains, for example, aTCO material for instance indium-tin oxide (ITO) or zinc oxide (ZnO).

The semiconductor device 1 further comprises a contact structure 4 forexternal electrical contacting of the semiconductor layer 21. Thecontact structure 4 comprises a contact area 41 for electricalcontacting, for example, by a wire bond connection. Ribs 42 for currentdistribution extend from the contact area 41 over the radiation exitface 210. The arrangement of the ribs 42, the position and numberthereof may be varied within broad limits. For example, the contactstructure may take the form of a closed frame extending along the sidefaces of the semiconductor device 1.

The contact area 41 is preferably configured such that charge carrierinjection under the contact area is prevented or at least reduced. FIGS.1B to 1D show various examples of this. Apart from the above, there areno other differences between these examples.

In the example shown in FIG. 1B, the contact structure directly adjoinsthe semiconductor layer 21. In this region a cutout is formed in thecurrent spreading layer. The electrical contact between the contact area41 and the semiconductor layer is deliberately configured such thatsubstantially no direct charge carrier injection takes place from thecontact area 41 into the semiconductor layer 21. In particular, there isno direct ohmic connection between the contact area and thesemiconductor layer.

In the example shown in FIG. 1C, the current spreading layer 3 and thecontact area 41 overlap. In particular, the current spreading layer 3extends continuously under the contact area. To prevent charge carrierinjection under the contact area, an insulation layer 6 is arrangedunder the contact area 41 between the current spreading layer 3 and thesemiconductor layer 21. The insulation layer contains an oxide or anitride, for example. Neither the contact area 41 nor the currentspreading layer 3 directly adjoin the semiconductor layer 21 under thecontact area.

In the example illustrated in FIG. 1D, the insulation layer 6 comprisesa cutout 65, unlike in FIG. 1C. In plan view onto the semiconductordevice 1, the contact area 41 and the cutout overlap. In the cutout 65the contact area 41 directly adjoins the semiconductor layer 21. Thecontact area therefore extends in places through the current spreadinglayer 3 and the insulation layer 6. The electrical contact between thecontact area 41 and the semiconductor layer is deliberately configuredsuch that substantially no direct charge carrier injection takes placefrom the contact area 41 into the semiconductor layer 21.

Furthermore, the semiconductor device 1 comprises a further contactstructure 5 with a further contact area 51 and a further rib 52. Thefurther contact structure 5 is provided for external electricalcontacting of the further semiconductor layer 22. The further contactstructure 5 is arranged in a recess 25 in the semiconductor body withthe semiconductor layer sequence 2. The recess 25 extends through thesemiconductor layer 21 and the active region 20 into the furthersemiconductor layer 22.

The semiconductor layer sequence 2 is arranged on a carrier 29. Anexample of a suitable carrier is a growth substrate in particular forepitaxial deposition of the semiconductor layers of the semiconductorbody 2, for example, by MOVPE. For example, the carrier 29 contains aradiation-transmissive material, for instance sapphire, gallium nitrideor silicon carbide. Another material may however also be used, forexample, silicon.

The current spreading layer 3 is arranged in a connection region 30 onthe semiconductor layer 21 and adjoins the semiconductor layer. Theconnection region 30 extends within an outer border of rectangular basicshape. Within this border, the current spreading layer comprises apatterning 31 with a plurality of recesses 35.

Various examples of the patterning are shown on the basis of a portion91 and a further portion 92 in FIGS. 2A to 2J and FIG. 3, respectively.

The patterning recesses are each configured such that radiation may exitthrough the recesses when the semiconductor device is in operation.Regions of the semiconductor device 1 in which the radiation exit face210 is free of the current spreading layer, for example, optionally toproduce electrical contacting by the contact structure 4 as shown forinstance in FIG. 1B or 1D, or the further contact structure 5, on theother hand do not constitute any such recesses. No radiation can exitfrom the semiconductor device at these locations due to theradiation-opaque, for example, metallic configuration of the contactstructure 4 and of the further contact structure 5.

The recesses 35 may extend vertically right through the currentspreading layer 3 or take the form of blind holes which end in thecurrent spreading layer. Recesses which extend through the currentspreading layer, i.e., cutouts, are particularly simple to produce andminimize absorption in the regions of the recesses. In recesses notextending right through the current spreading layer, the currentspreading layer also adjoins the semiconductor layer 21 in the region ofthe recesses. Current injection into the semiconductor layer 21 over amaximally large area is thus simplified.

The crosswise extent of the recesses preferably amounts to 2 μm to 100μm, particularly preferably 2 μm to 50 μm. The crosswise extent is hereunderstood to mean the maximum extent perpendicular to a longitudinaldirection in which the recess exhibits its maximum extent. FIG. 2A showsby way of example a lengthwise extent 351 and a crosswise extent 352 forelliptical recesses 35.

The maximum crosswise extent of the recesses over which completeenergization of the active region takes place even in the recessesdepends in particular on the transverse conductivity of thesemiconductor layer 21 to be electrically contacted.

The lengthwise extent of the recesses may on the other hand also be verymuch greater than the crosswise extent, provided the smallest distancewithin the recesses to the closest location of the current spreadinglayer is no greater than the current spreading length in thesemiconductor layer 21.

The recesses 35 result in regions on the radiation exit face 210 fromwhich radiation is able to exit from the semiconductor device withouthaving to pass through the entire thickness of the current spreadinglayer 3. This reduces the fraction of radiation absorbed overall in thesemiconductor device. The lateral extent of the recesses is configured,in plan view onto the semiconductor device, such that, when thesemiconductor device 1 is in operation, at every location in therecesses charge carriers may be injected via the semiconductor layer 21into the active region 20. This prevents locations from being able toarise in the active region under the recesses 35 which are not energizedand cause increased absorption during operation. Such absorption mightmore than compensate for the reduced absorption through the currentspreading layer 3 due to the recesses 35.

By the patterning 31 of the current spreading layer 3, minimizedradiation absorption and efficient charge carrier injection are thuscombined.

Within the connection region 30, coverage with material of the currentspreading layer 3 may be varied. As a measure of coverage with materialof the current spreading layer, a square may, for example, be used whichhas an edge length which is greater than or equal to twice the crosswiseextent of the recesses. This square shows different coverage atdifferent locations of the connection region 30. FIG. 1A shows, by wayof example, a first square area 81 and a second square area 82 ofidentical size, wherein the first square area 81 is closer to theclosest border of the contact structure 4 than the second square area82. Preferably, the recesses in the first square area fill at least 50%of the first square area and the recesses in the second square area fillat most 10% of the second square area.

Coverage with material of the current spreading layer 3 may, forexample, increase in a linear manner or by a higher order of magnitudeas the distance from the closest border of the contact structure 4increases. For example, coverage increases proportionally to wherein xis the distance and 0≦n≦1. Regions which are close to the contactstructure 4 and in which therefore comparatively major charge carrierinjection into the active region 20 takes place via the semiconductorlayer 21 therefore have comparatively low coverage with material of thecurrent spreading layer 3. Due to the increased radiation emission inthese regions, the absorption losses reduced by the recesses 35 herehave a particularly favorable effect on the efficiency of thesemiconductor device 1. Regions further away from the contact structure4 are, on the other hand, less strongly energized due to the longercurrent path in the current spreading layer 3, in particular if thetransverse conductivity of the semiconductor layer 21 is lower than thetransverse conductivity of the further semiconductor layer 22.

By varying coverage with the current spreading layer 3 by the patterning31, it is in particular possible to achieve a homogeneous currentdensity and/or a homogeneous luminance.

Preferably, the patterning 31 of the current spreading layer 3 and theexternal border of the current spreading layer are free of angularedges. The risk of current and/or voltage peaks, which could lead toheating or even to destruction of the semiconductor device 1, is thusavoided.

The distance between the recesses 35 closest to the contact structure 4and the contact structure 4 is preferably such that the recesses do notor at least do not significantly impair distribution of the current inthe current spreading layer.

In the example of the patterning 31 shown in FIG. 2A, the recesses 35are arranged in a matrix. The lengthwise extent of the recesses 35extends perpendicular to the border of the closest contact structure 4.Current flow within the current spreading layer 3 in a preferentialdirection of the current between the contact structure 4 and the furthercontact structure 5 may thus extend continuously between the recesses35. This keeps the current path small which the charge carriers have tocover in the current spreading layer 3 to energize the active region 20.

Unlike circular recesses with elongate, for example, ellipticalrecesses, the area of the recesses may be enlarged without the maximumdistance to the closest location of the current spreading layer 3increasing. For example, the point at maximum distance in an ellipse isthe center point of the ellipse and the maximum distance corresponds tohalf the transverse axis of the ellipse.

In the example shown in FIG. 2B, the recesses 35 are likewise ofelongate configuration and have a trench-like basic shape. Thetrench-like recesses 35 extend parallel to one another such that ribs 33of the current spreading layer 3 arise between these trenches. Thetrench-like recesses 35 may also, as in FIG. 2C, extend as far as theedge of the current spreading layer 3, resulting in places in acomb-like patterning 31.

The crosswise extent of the trench-like recesses 35 and/or of the ribs33 may also vary as shown in FIG. 2D. Preferably, a crosswise extent ofthe trench-like recesses decreases at least in places as the distancefrom the contact structure 4 increases. The radiation exit face 210 thusin turn has lower coverage with the current spreading layer 3 close tothe contact structure 4 than in a region further away from the contactstructure 4. The crosswise extent of the trench- like recesses and/orthe crosswise extent of the ribs 33 may vary in the connection region,for example, by at least 50%.

FIGS. 2E to 2H show various configurations in which coverage withmaterial of the current spreading layer 3 is varied. In the exampleaccording to FIGS. 2E and 2F, coverage varies by variation of thecrosswise extent of the recesses 35. In the example shown, the recesses35 are of circular construction. In contrast thereto, however, they mayalso have an elongate basic shape, for example, an elliptical basicshape.

FIGS. 2G and 2H each show examples in which coverage varies by variationof the average distance between neighboring recesses 35. In the examplesshown in FIGS. 2F and 2H, the recesses 35 are each arranged such thatcontinuous current paths form between the recesses 35 perpendicular tothe contact structure 4. This configuration conveys a local current flowalong a preferential direction perpendicular to the closest contactstructure 4.

The configurations shown in FIGS. 2E and 2G, in which parallel rows ofrecesses are arranged offset relative to one another along the contactstructure 4 are suitable in particular for regions of the currentspreading layer in which there is no preferential directionperpendicular to the contact structure 4. As a result of the arrangementshown of the recesses, which corresponds locally at least approximatelyto a hexagonal grid, the density of the recesses increases at a constantdistance between neighboring recesses.

FIGS. 21 and 2J show two examples in which optical information 39 isformed by the patterning 31. In the example shown in FIG. 21, theoptical information 39 is formed by letters, in the example shown by acharacter string “OSRAM.” Other types of letters, characters orgraphical symbols such as logos are also suitable as opticalinformation. Preferably, the letters or elements are configured suchthat they have only a slight effect on current flow in the currentspreading layer. In the example shown, the individual letters each havean elongate shape perpendicular to the contact structure 4.

In the example shown in FIG. 2J, the patterning 31 comprises a pluralityof first recesses 35 a and a plurality of second recesses 35 b, whichdiffer in size and are arranged in a matrix. These two different typesof recess allow optical information to be encoded in digital form.

By purposeful variation of the area and/or shape of the recesses,optical information can therefore be represented without this having tohave a major effect on the performance of the semiconductor device.

The optical information is particularly suitable for traceability of thesemiconductor devices produced and may, for example, contain informationrelating to production, for example, relating to the manufacturer itselfto the batch or to the position of the produced semiconductor chip onthe wafer from which it originates. For example, 16 bit information,i.e., information about 65,536 different positions on the wafer, can beindicated by 16 recesses.

The information may also be encoded in another form, for example, byvarying the shape of the recesses. Furthermore, it is possible, forexample, with elongate recesses, for instance trench-like recesses toencode optical information in the form of a barcode.

FIG. 3 shows an example of a patterning on the basis of a furtherportion 92. This further portion 92 is located in a region of thecurrent spreading layer 3 in which the adjacent contact structure 4 doesnot extend in a straight line throughout. The contact structure 4comprises two kinks. In such a region no large-area uniform preferentialdirection is established for the current flow within the currentspreading layer. In such regions, an arrangement of recesses in apattern having no significant current effect, for example, a honeycombpattern, is, for example, particularly suitable.

FIG. 4 is a schematic diagram of the luminance distribution L of asemiconductor device without patterning of a current spreading layer.The luminance L and the dimensions along the x axis and the y axis areexpressed in arbitrary units (a.u.).

In various regions of the semiconductor device 1 it is possible, asshown in FIG. 4, to dispense deliberately with formation of a currentspreading layer 3. This is convenient in particular for peripheralregions or corner regions, in which, due to the arrangement of thecontact regions, only comparatively slight charge carrier injection intothe underlying active region would take place even if a currentspreading layer were provided. This may also be convenient for innerregions in which only slight charge carrier injection would take place.These are, for example, regions of the semiconductor device in whichcurrent density is below 20% of the average current density. Freeregions 38 at these locations may increase outcoupling of the radiationgenerated, which may arise at any desired position within the activeregion 20.

This application claims priority of DE 10 2014 108 300.8, the subjectmatter of which is hereby incorporated by reference.

Our devices are not restricted by the description given with referenceto the examples. Rather, the disclosure encompasses any novel featureand any combination of features, including in particular any combinationof features in the appended claims, even if the feature or combinationis not itself explicitly indicated in the claims or the examples.

1-15. (canceled)
 16. An optoelectronic semiconductor device having asemiconductor body comprising a semiconductor layer sequence with anactive region that generates radiation, a semiconductor layer and afurther semiconductor layer, wherein the active region is arrangedbetween the semiconductor layer and the further semiconductor layer; acurrent spreading layer is arranged on a radiation exit face of thesemiconductor body; the current spreading layer connects electricallyconductively with a contact structure for external electrical contactingof the semiconductor layer; in a plan view of the semiconductor devicethe current spreading layer adjoins the semiconductor layer in aconnection region; and the current spreading layer comprises apatterning with a plurality of recesses through which radiation exitsthe semiconductor device during operation.
 17. The semiconductor deviceaccording to claim 16, wherein the recesses are at least partly elongatewhen viewed in the plan view of the semiconductor device, and in alongitudinal direction the recesses have a lengthwise extent at least20% greater than a crosswise extent in a transverse direction extendingperpendicular to the longitudinal direction.
 18. The semiconductordevice according to claim 17, wherein the crosswise extent is conformedto a transverse conductivity of the semiconductor layer such that, inthe plan view of the semiconductor device, charge carriers are injectedvia the semiconductor layer into the active region at every location inthe recesses during operation of the semiconductor device.
 19. Thesemiconductor device according to claim 17, wherein the patterningcomprises trench-shaped recesses with ribs of the current spreadinglayer extending between the trench-shaped recesses and a crosswiseextent of the trench-shaped recesses decreases at least in places as thedistance from the contact structure increases.
 20. The semiconductordevice according to claim 16, wherein an area of the recesses and/or acenter-to-center distance of the recesses varies, when viewed in theplan view of the semiconductor device.
 21. The semiconductor deviceaccording to claim 16, wherein the connection region comprises a firstsquare area and a second square area, the first square area and thesecond square area are of equal size and each have an edge length whichis greater than or equal to twice the crosswise extent of the recessesin the first square area, and wherein, in the plan view of thesemiconductor device, the recesses in the first square area fill atleast 20% of the first square area and the recesses in the second squarearea fill at most 10% of the second square area.
 22. The semiconductordevice according to claim 21, wherein the first area is arranged closerto a closest point of the contact structure than the second area. 23.The semiconductor device according to claim 16, wherein the recesses donot extend right through the current spreading layer in a verticaldirection extending perpendicular to the main plane of extension of thesemiconductor layer sequence.
 24. The semiconductor device according toclaim 16, wherein the recesses take the form of cutouts extendingthrough the current spreading layer.
 25. The semiconductor deviceaccording to claim 16, wherein, in the plan view of the semiconductordevice, the patterning contains optical information.
 26. Thesemiconductor device according to claim 16, wherein the patterningcomprises at least one first recess and one second recess, and the firstrecess and the second recess differ from one another in their base areain the plan view of the semiconductor device.
 27. The semiconductordevice according to claim 26, wherein the patterning comprises aplurality of first recesses and a plurality of second recesses andinformation is encoded by the first recesses and the second recesses.28. The semiconductor device according to claim 16, wherein thepatterning is configured such that, in a region in which current flowlocally has a preferential direction in the current spreading layer, thepatterning favors lateral current flow in the preferential direction.29. The semiconductor device according to claim 16, wherein thepatterning is configured such that, in a region in which a current flowis locally without a preferential direction, the patterning has no or atleast no significant effect on the direction of the lateral currentflow.
 30. The semiconductor device according to claim 16, wherein, in aregion of the semiconductor device in which a current density is below20% of the average current density, the radiation exit face is free ofthe current spreading layer to increase the radiation outcoupling fromthe semiconductor device.
 31. An optoelectronic semiconductor devicehaving a semiconductor body comprising a semiconductor layer sequencewith an active region that generates radiation, a semiconductor layerand a further semiconductor layer, wherein the active region is arrangedbetween the semiconductor layer and the further semiconductor layer; acurrent spreading layer is arranged on a radiation exit face of thesemiconductor body; the current spreading layer connects electricallyconductively to a contact structure for external electrical contactingof the semiconductor layer; in a plan view of the semiconductor device,the current spreading layer adjoins the semiconductor layer in aconnection region; the current spreading layer comprises a patterningwith a plurality of recesses through which radiation exits thesemiconductor device during operation; and the patterning comprisestrench-shaped recesses with ribs of the current spreading layerextending between the trench-shaped recesses and a crosswise extent ofthe trench-shaped recesses decreases at least in places as the distancefrom the contact structure increases.